Field of the Invention
The present invention relates to working of tubes coupled to a tubesheet and, more particularly, to the use of robotics and light sources for such working.
Description of Related Art
In nuclear steam generator and balance of plant eddy current inspections, robots are often used to position a tool in alignment with one or more given tubes, one-at-a-time, in a tubesheet. The robot has an end-effector that supports the tool in position to be fed into holes in the tubesheet. The tool must be positioned directly in alignment with the tube to be inspected in order for the tool to run smoothly through the hole in a tubesheet and into the tube in fluid communication with the hole in the tubesheet.
Typically, a camera mounted on the end-effector is utilized to monitor the alignment of the tool to a particular hole in the tubesheet. Because the viewing axis of the camera is mounted transverse to the axis of the tubesheet and, hence, the hole desired to be aligned with the tool, an image of the end of the tool and the hole being aligned therewith suffers from a condition known as parallax which is the apparent displacement of an observed object due to a change in the position of the observer.
Because of this parallax, it is not uncommon to misalign the tool and a hole in a tubesheet, whereupon the tool cannot be successfully inserted into the desired hole in the tubesheet because of this misalignment. Because the insertion of the tool into each tube is often controlled by a motorized drive, there is a chance when the tool is misaligned with a hole in the tubesheet that the motorized drive will push the tool into the face of the tubesheet, instead of the hole thereby potentially damaging the tool.